X and Y crash into limits during homing

[bybon]

The Z homing acts as it should.  Unfortunately, when the X and Y find home, my limit switches fail to operate.   The motors just gring as the push into the machine itself.  I did check on the set-up, and when touched by hand, they light up in the program.  Using the command line, they read  $20=0  (soft limits enable, boolean)   $21=1 hard limits enable, boolean.  I thought the the $20-0 was meant to disable?  Anyway, what exactly do I do and go to edit this $$.  Thanks.  This is for my M3.  Thanks

[Bruce]

Both hard and soft limits should be set to = 0  See the M3 default settings below. To change the setting just type in $21=0 then press enter. 



M3 Default GRBL settings:

$0=10 (step pulse, usec)

$1=255 (step idle delay, msec)

$2=0 (step port invert mask:00000000)

$3=0 (dir port invert mask:00000000)

$4=0 (step enable invert, bool)

$5=0 (limit pins invert, bool)

$6=0 (probe pin invert, bool)

$10=3 (status report mask:00000011)

$11=0.010 (junction deviation, mm)

$12=0.002 (arc tolerance, mm)

$13=0 (report inches, bool)

$20=0 (soft limits, bool)

$21=0 (hard limits, bool)

$22=0 (homing cycle, bool)

$23=0 (homing dir invert mask:00000000)

$24=25.000 (homing feed, mm/min)

$25=600.000 (homing seek, mm/min)

$26=244 (homing debounce, msec)

$27=4.000 (homing pull-off, mm)

$30 = 12000 (Maximum spindle speed, RPM)
$31 = 0 (Minimum spindle speed, RPM)
$32 = 1 (Laser-mode enable, boolean)

$100=40.000 (x, step/mm)

$101=40.000 (y, step/mm)

$102=80.000 (z, step/mm)

$110=8000.000 (x max rate, mm/min)

$111=8000.000 (y max rate, mm/min)

$112=3000.000 (z max rate, mm/min)

$120=250.000 (x accel, mm/sec^2)

$121=250.000 (y accel, mm/sec^2)

$122=250.000 (z accel, mm/sec^2)

$130=264.000 (x max travel, mm)

$131=264.000 (y max travel, mm)

$132=69.000 (z max travel, mm)

[bybon]

Thank you for the aid. Went to command line and typed $20=0 and $21=0 and they now read: $20=0 (soft limits enable, boolean) and $21=0 (hard limits enable, boolean). Turned all off and restarted. Did the $$ again and it still reads like above. I may be missing something obvious. X anf Y still crash into their limits with a growl.

I will go line by line to see if mine differs from defaults.

[joebob296]

I know you said they light up in the program does that mean you used the show verbose output option in UGS?

[bybon]

Yes it does. And when I stated the individual axis light up, it was in setup Wizard in the limit switch test. Thanks

[Derek the Admin]

If your switches register when you touch them but you have a crash on homing I expect you have one of three situations:
1) Switches are crossed (x on y, y on x)
2) pull off value is wrong
3) switches are too far to the end if travel and the engager can't fully engage it to give a firm throw of the switch

[bybon]

Thank you.  Yep, the wires were switched.  Took all limit switches off, their wires and connectors.  Soldered all again and did the install over.  Worked perfectly.  Thanks again!